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• avformat/mov : Handle when we have an mfra box but have not read the full sidx for...

  15 mars 2021, par Derek Buitenhuis

  avformat/mov : Handle when we have an mfra box but have not read the full sidx for a fragment
  Use the tfra timestamp if it is available and sidx timestamp is not.
  Fixes reading the entire file after seeking in a live-style DASH FMP4
  
  with an MFRA.
  This specifically fixes when use_mfra_for is set.
  Signed-off-by : Derek Buitenhuis <derek.buitenhuis@gmail.com>
  

  • [DH] libavformat/mov.c

• Recording of Full HD 60 FPS videos in C#

  17 mars 2021, par Alexander Naumov

  My application works with a high-speed camera. I am trying to record a videofile using C#.

  


  The task is pretty "simple" : to record the video from the camera. We need to record medium (higher-better) quality videos to save as many details as possible.

  


  

  • Resolution : 1920 x 1080 (FullHD)

  


  • Frames per second (FPS) : 60

  


  • Bitrate : I've started from 10000*1000 (but now I don't know)

  


  • Mediacontainer : MP4, AVI (does not really matter, we just need to
solve our task)

  


  • Codec : also does not matter, we just need speed and quality.

  


  • Maximum size of videofile : 10 GB/hour

  


  


  Framerate of the camera can be changed during the recording by the camera itself (not by user), so it's necessary to have something like timestamps for every frame or anything else.

  


  The problem is not fast enough recording.
Example : using AForge libs, generated pictures ("white" noise), duration of test videos is 20 seconds.

  


  Duration of video creating using different codecs (provided by AForge) :

  


  

  • Codec : MPEG4, Time : 33,703

  


  • Codec : WMV1, Time : 45,338

  


  • Codec : WMV2, Time : 45,530

  


  • Codec : MSMPEG4v2, Time : 43,775

  


  • Codec : MSMPEG4v3, Time : 44,390

  


  • Codec : H263P, Time : 38,894

  


  • Codec : FLV1, Time : 39,151

  


  • Codec : MPEG2, Time : 35,561

  


  • Codec : Raw, Time : 61,456

  


  


  Another libs we've tried is not satisfied us.
Accord.FFMPEG is slow because of strange inner exceptions.
EmguCV.FFMPEG has no timestamps, therefore it creates corrupted video.

  


  Recording the video to the SSD drive did not give us any visible acceleration.

  


  Google search gives no clear examples or modern solutions to solve this task. That's the main reason to write here.

  


  There is a code sample of our test :

  


  private static void AForge_test()
    {
        Console.WriteLine("AForge test started...");
        unsafe
        {
            Stopwatch watch = new Stopwatch();

            Console.WriteLine("FPS: {0}, W:{1}, H:{2}, T:{3}", fps, w, h, time);

            AForge.Video.FFMPEG.VideoCodec[] codecs = (AForge.Video.FFMPEG.VideoCodec[]) Enum.GetValues(typeof(AForge.Video.FFMPEG.VideoCodec));

            for(int k = 0; k < codecs.Length; k++)
            {
              /*  if (codecs[k] != VideoCodec.MPEG4)
                    continue;*/
                try
                {
                    watch.Restart();

                    Random r2 = new Random(200);
                    AForge.Video.FFMPEG.VideoFileWriter vw = new AForge.Video.FFMPEG.VideoFileWriter();
                    string name = String.Format("E:\\VideosHDD\\AForge_test_{0}_mid.avi", Enum.GetName(typeof(AForge.Video.FFMPEG.VideoCodec), codecs[k]));
                    vw.Open(name, w, h, fps, codecs[k], 10000 * 1000);

                    for (int i = 0; i < frames; i++)
                    {
                        vw.WriteVideoFrame(bmps[i%N]);
                    }

                    vw.Close();
                    vw.Dispose();

                    watch.Stop();

                    Console.WriteLine("Codec: {0}, Time: {1:F3}", Enum.GetName(typeof(AForge.Video.FFMPEG.VideoCodec), codecs[k]), watch.ElapsedMilliseconds / 1000d);
                }
                catch(Exception ex)
                {
                    Console.WriteLine("Error " + codecs[k].ToString());
                }

            }
            
        }

        Console.ReadKey();
    }


  


  Additional :

  


  

  1. We are ready to use not-for-free solutions, but free is preferable.

  


  2. One of the supposed reasons for low recording speed : (x86) building of applications. I tried so hard to find x64 Aforge building but failed in this. We really don't know is there any influence of application architecture on recording speed.

  


  


  I am ensured that I don't know all the background of video recording and another "little" thing, so I would be very pleased to solutions with clear explanations.

  


• avcodec/ljpegenc : Allow full range yuv420p, yuv422p, yuv444p by default

  6 avril 2021, par Andreas Rheinhardt

  avcodec/ljpegenc : Allow full range yuv420p, yuv422p, yuv444p by default
  The documentation for AV_PIX_FMT_YUVJ420P reads :
  
  "planar YUV 4:2:0, 12bpp, full scale (JPEG), deprecated in favor of
  
  AV_PIX_FMT_YUV420P and setting color_range"
  
  Yet the LJPEG encoder only accepts full scale yuv420p when strictness is
  
  set to unofficial or lower ; with default strictness it emits a nonsense
  
  error message that says that limit range YUV is unofficial. This has
  
  been changed to allow full range yuv420p, yuv422p and yuv444p irrespective
  
  of the level of strictness.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/ljpegenc.c